Jennifer Hudson's Mother and Brother Fatally Shot

Jennifer Hudson's mother and brother were the two victims of a fatal shooting in Chicago, the actress's publicist says.

"We can confirm that there is an ongoing investigation concerning the deaths of Jennifer Hudson's mother, Darnell Donerson, and her brother, Jason Hudson," rep Lisa Kasteler tells PEOPLE. "No further comment will be made and the family has asked that their privacy be respected at this difficult time."

The victims' bodies were found by officers Friday in a South Side home listed in the name of Hudson's mother, and police say the shooting appeared to be related to a domestic disturbance.

Hudson's 7-year-old nephew, Julian King, is missing. An Amber Alert has been issued for him.

"We are searching for a young boy from that address who is missing," says Chicago police spokesman Officer John Mirabelli.

A man authorities were searching for in connection with the shootings, identified as William Balfour, 27, has been taken into custody and is being questioned by authorities, the Associated Press reports. No charges have been filed.

According to the AP, police spokeswoman Monique Bond says police are talking to "a number of people in custody" but she declined to further elaborate.

Hudson, 27, the Oscar-winning actress from Dreamgirls and an American Idol alum, recently got engaged to boyfriend David Otunga. She stars in the current film The Secret Life of Bees.